The present invention relates to a device and a method for warning motorists that the air pressure in one or more of their tire is low.
Most automobiles, trucks, trailers, and recreational vehicles use air-inflated (pneumatic) tires. Safe operation of these vehicles depends upon the maintenance of proper tire pressure in the tires. Frequently, tires lose pressure as the result of air seepage from around the valve stem or from punctures. This loss of air and the accompanying decrease in tire pressure can adversely effect the performance of the vehicle and presents a safety hazard.
Low air pressure in the tires leads directly to increased and abnormal temperature and wear of the tires. This wear and heat may result in a blowout of the underinflated tire. Blowouts present a serious hazard to the driver, passengers, and fellow motorists and cost the driver time and money. Blowouts are particularly dangerous on trucks, trailers, and recreational vehicles because these vehicles are generally less table and harder to handle than automobiles. Therefore, an early warning system for potential tire failure is especially valuable for the operators of these vehicles.
The need for warning of an imminent blowout has led others to create devices which attempt to detect low pressure in tires. None of these devices has proved to be commercially practical, however. The existing methods for warning motorists of low tire pressure are predominantly valve stem connected and activated by a spring biased valve that protrudes from the valve stem when low pressure occurs within the tire U.S. pat. Nos. 3,533,063; 4,031,845; 4,067,376; 4,131,877; 4,135,285; 4,186,377; and 4,165,579). Other devices are activated if a feeler arm comes in contact with the ground when the tire pressure is very low (U.S. Pats. Nos. 3,413,598; 4,173,011; and 3,055,998).
Once the currently available devices are activated, there are a variety of methods for notifying the driver of the decreased pressure. Among these methods are radio transmitters (U.S. Pat. No. 3,533,063) and whistling sounds (U.S. Pat. No. 4,135,285). The existing devices have a variety of drawbacks including expense, undependability, lack of sensitivity, and not being activated when one tire of dual mounted tires has low air pressure.